Overheating or Not?

[Jim Cate]

Originally Posted by TopperHarley

ok... So the IR thermometer aarrived in the post today.... Ill be taking it down to the boat in the next few days...

Any specific suggestions as to how to continue with the troubleshooting ?

Expected temps at which locations etc ??

Hard to give any specific temperatures or spots since I am not familiar with your engine. But I think what you should be looking for is any spot on the surface of the engine that is much above what your coolant temp gage shows... something must be getting pretty hot to emit the smells that you report. In general with raw water cooling one should be below 160 F or so (different sources quote different max temps). Exceeding that value leads to salt deposits being developed in the coolant passages.

Our previous boat had a raw water cooled BMW D-35 engine, and it suffered from such deposits chronically. A BMW agent in San Diego told us to flush it with dilute HCl on a regular basis, and we did so every year or two during the 17 years that we had that boat. This process helped, but eventually it got away from us and we had to take off the head and resort to physical chipping and extensive acid washing to get it clean again. So, if the investigation does reveal hot spots, an acid wash/soak may restore normal operation. If you do this, be sure to remove any internal zinc anodes before applying the HCl... they will be destroyed and will reduce the efficacy of the acid to boot!

Good luck with it, mate!

Jim

[GILow]

All of my car engine block sensors in the past have been set to trip at around 80 degrees C, so I should expect temperatures would not be a lot higher than that. I know no part of my Nissan gets that hot though, at least no part I have found.

Still, this is just me guessing, I will be as curious as you to hear what the experienced cruisers have found. And I am really interested to see what you find, for something to smell too hot I would think you would find some point at well over 100 degrees C.

Sorry, not contributing anything useful here, but I am just plain curious to see what is going on.


Matt

[DeepFrz]

Perhaps the engine re-builder put in a thermostat for a heat exchange cooled engine which will be way to hot for a raw water engine. It will cause the salt to precipitate out and plug up your engines cooling passages.

Edit: by the way, too hot to touch is a relative thing and so is really useless as a guide to temp.

[pbiJim]

Please be aware that the IR thermometers are affected by the color of the item being measured. Most are calibrated for use with a flat black surface. The device should have come with instructions that include information on interpreting the readings on items that are shiny &/or different colors.

[Rakuflames]

Originally Posted by TopperHarley

ok... So the IR thermometer aarrived in the post today.... Ill be taking it down to the boat in the next few days...

Any specific suggestions as to how to continue with the troubleshooting ?

Expected temps at which locations etc ??

When I was having overheat problems I picked a spot on the block and marked it with indelible pen. My old engine at that time did not have a temp gauge and was overheating very unpredictably -- sometimes after running 30 min.; sometimes after running 2 hours.

Using the IR meter periodically gave me a consistent way to gauge the building heat.

The final indicator was that the engine would blow steam instead of water out the exhaust 30 seconds before the alarm went off. To me that was too late a warning. The IR meter allowed me to take steps to cool the engine down before it was an extreme problem.

I think the engine was eaten up by elctrolysis. Someone has it and will take it apart eventually and try to get it going. Until then I won't know for sure. But there were indications that the zincs had been seriously neglected before I got it.

Now I have a new engine and it is soooo wonderful to have a dependable engine.

[bobconnie]

If I understand you, this engine is RAW WATER cooled right?? If so 170/180 is way to hot!! should be under 150deg F. If not raw water cooled then your gonna need that new tool !!

[bill good]

Can I join in too? I've been flogging my 1GMs for some 1200nms due to headwinds both ways to the Whitsundays & back instead of just sailing. The engines are in a tight box without a lot of air. Over heat warnings will develop after shut down & last for hours so I am thinking a blower in the front of the engine bay to ensure positive pressure is maintained during running & provide air flow for cooling after shut down. The Yanmar people tell me I need air intake surface of 50 CM sq & the same for air outlet. (I am sus that the little motors are sucking the inspection hatches down due to a small negative air pressure at high power settings) That translates to leaving the covers off the engines with a lot of extra noise inside the boat!! Blowers are quoted in cubic metres per minute. Any one with advice before I make the next mod. & mistake??

Regards Bill

[Strait Shooter]

Originally Posted by bobconnie

If I understand you, this engine is RAW WATER cooled right?? If so 170/180 is way to hot!! should be under 150deg F. If not raw water cooled then your gonna need that new tool !!

I have an M60 Perkins that's raw water cooled and it runs around 180 degrees.